Conditions characterized by cellular hyperproliferation, such as chronic inflammation, ischemic diseases, and cancer are often accompanied by intense angiogenesis, a highly orchestrated process involving vessel sprouting, endothelial cell migration, proliferation, and maturation. Endothelial cells are normally quiescent but become activated during the angiogenic response. Upon stimulation, endothelial cells can degrade their basement membrane and proximal extracellular matrix, migrate directionally, then divide and organize into functional capillaries invested by a new basal lamina.
Posterior segment neovascularization (NV) is the vision-threatening pathology responsible for the two most common causes of acquired blindness in developed countries: exudative age-related macular degeneration (wet AMD) and proliferative diabetic retinopathy (PDR). Currently there are several approved treatments in the United States for treating the posterior segment NV that occurs during wet AMD. Laser photocoagulation involves thermal destruction of the neovascular lesion with a laser, which because of the vagaries of laser targeting and thermal energy transfer leads to collateral destruction of some surrounding tissue. Photodynamic therapy with Visudyne® solution involves intravenous administration of the solution to the patient, after which time a red laser is shone into the AMD-affected eye(s). The resultant photon absorption by the porphyrin active ingredient produces an electronically excited state that transfers energy to oxygen to produce reactive oxygen species. Use of strictly pharmacological therapies commenced in late 2004 with the approval in the United States of the VEGF-binding aptamer pegaptanib sodium (Macugen® solution) for the treatment of wet AMD. Surgical interventions with vitrectomy and membrane removal are the only options currently available for patients with proliferative diabetic retinopathy. Other pharmacologic treatment being evaluated clinically for the treatment of wet AMD and for diabetic retinopathy include anecortave acetate (Alcon, Inc.) and rhuFabV2 (Genentech) for AMD and LY333531 (Lilly) and Fluocinolone (Bausch & Lomb) for diabetic macular edema.
Non-exudative (dry) AMD can progress to wet AMD as described below. In a normally functioning retina, photoreceptors are supported by specialized cells in the retinal pigmented epithelium (RPE). These RPE cells take up released 11-trans retinaldehyde (in the form of the reduced retinol) and isomerize the olefin geometry back to the photoactive 11-cis form. RPE cells also phagocytose photoreceptor outer membrane segments that are continuously shed and replaced. Choroidal capillaries provide nutritional support (oxygen, proteins, hormones, etc.) to and remove waste products from photoreceptors and RPE cells, and are separated from them by Bruch's membrane. It is believed that a normally functioning Bruch's membrane is sufficiently permeable to allow diffusional exchange of nutrition and waste products between the choroidal capillaries and RPE cells. In dry AMD there is increased deposition of insoluble material within Bruch's membrane, leading to protein cross-linking. The accumulation of hydrophobic material may be a consequence of inefficient phagocytosis, and may precipitate an inflammatory response. Over time the membrane thickens and consequently has decreased permeability both to oxygen (and plasma-borne nutrients) from the choroidal capillaries and to waste products from RPE cells. RPE cells may die from the resulting metabolic distress. Without their RPE support cells, the associated photoreceptors in the macula die. This loss of macular photoreceptors is termed geographic atrophy. As the photoreceptors die, central visual acuity is gradually lost. Additionally, RPE cells may respond to the hypoxic condition resulting from Bruch's membrane thickening by secreting pro-angiogenic proteins in an attempt to re-establish adequate blood flow. The most important of these proteins is vascular endothelial growth factor (VEGF). VEGF promotes the proliferation of new capillaries from existing ones, and these breach Bruch's membrane. This leads to macular accumulation of fluid and blood from the leaky new vessels (VEGF is a potent blood vessel permeability-increasing factor) and formation of fibrous deposits and scar tissue in the retina, rapidly causing retinal detachment and therefore loss of visual function. Thus treating dry AMD by rescuing RPE cells from metabolic distress-induced cell death should also inhibit disease progression to wet AMD.
With respect to diabetic retinopathy, in addition to changes in the retinal microvasculature induced by hyperglycemia in diabetic patients leading to macular edema, proliferation of neovascular membranes is also associated with vascular leakage and edema of the retina. Where edema involves the macula, visual acuity decreases. In diabetic retinopathy, macular edema is the major cause of vision loss. Like angiogenic disorders, laser photocoagulation is used to stabilize or resolve the edematous condition. While reducing further development of edema, laser photocoagulation is a cytodestructive procedure, that, unfortunately will decrease vision in the affected eye.
A pharmacologic therapy for ocular NV and edema would provide substantial efficacy to the patient, in many diseases thereby avoiding invasive surgical or damaging laser procedures. Effective treatment of the NV and edema would improve the patient's quality of life and productivity within society. Also, societal costs associated with providing assistance and health care to the blind could be dramatically reduced.
Excessive angiogenesis of the blood vessels in the synovial lining of the joints is thought to play an important role in rheumatoid arthritis. In addition to forming new vascular networks, the endothelial cells release factors and reactive oxygen species that lead to pannus growth and cartilage destruction. It is believed that the factors involved in angiogenesis can actively contribute to, and help maintain, the chronically inflamed state of rheumatoid arthritis. It is believed that factors associated with angiogenesis can also have a role in osteoarthritis. The activation of the chondrocytes by angiogenic-related factors contributes to the destruction of the joint. At a later stage, the angiogenic factors can promote new bone formation.
Often times, cancer is associated with angiogenesis and is identified by solid tumor formation and metastasis. A tumor cannot expand without a blood supply to provide nutrients and remove cellular wastes. Tumors in which angiogenesis is important include solid tumors, and benign tumors such as acoustic neuroma, neurofibroma, trachoma and granulomas. Prevention or inhibition of angiogenesis could prevent or halt the growth of these tumors and the subsequent degenerative condition due to the presence of the tumor.
Angiogenesis has also been associated with blood-born tumors including leukemias, any of the various acute or chronic neoplastic diseases of bone marrow in which unrestrained proliferation of white blood cells occurs, usually accompanied by anemia, impaired blood clotting, and enlargement of the lymph nodes, liver, and spleen. It is believed that angiogenesis is significant as a caustive factor in the abnormalities in the bone marrow that give rise to leukemia-like tumors.
Angiogenesis is important in two stages of tumor metastasis. The first stage where angiogenesis stimulation is important is in the vascularization of the tumor which allows tumor cells to enter the blood stream and to circulate throughout the body. Once the tumor cells leave the primary site, and find a secondary metastasis site, angiogenesis must occur before the new tumor can grow and expand. Therefore, prevention of angiogenesis could prevent metastasis of tumors and contain the cancerous growth to the primary site.
Many individuals suffer from heart disease caused by a partial blockage of the blood vessels that supply the heart with nutrients. More severe blockage of blood vessels in such individuals often leads to hypertension, ischemic injury, stroke, or myocardial infarction. Typically vascular occlusion is preceded by vascular stenosis resulting from intimal smooth muscle cell hyperplasia. The underlying cause of the intimal smooth muscle cell hyperplasia is vascular smooth muscle injury and disruption of the integrity of the endothelial lining. Restenosis is a process of smooth muscle cell migration and proliferation at the is site of percutaneous transluminal coronary balloon angioplasty, which hampers the success of angioplasty. For both vascular stenosis and restenosis secondary to balloon angioplasty, the overall disease process can be termed a hyperproliferative vascular disease because of the etiology of the disease process.
There are many agents known to inhibit angiogenesis. For example, steroids functioning to inhibit angiogenesis in the presence of heparin or specific heparin fragments are disclosed in Crum, et al., A New Class of Steroids Inhibits Angiogenesis in the Presence of Heparin or a Heparin Fragment, Science, Vol. 230:1375-1378, Dec. 20, 1985. The authors refer to such steroids as “angiostatic” steroids. Included within this class of steroids found to be angiostatic are the dihydro and tetrahydro metabolites of cortisol and cortexolone. In a follow-up study directed to testing a hypothesis as to the mechanism by which the steroids inhibit angiogenesis, it was shown that heparin/angiostatic steroid compositions cause dissolution of the basement membrane scaffolding to which anchorage dependent endothelia are attached resulting in capillary involution; see, Ingber, et al., A Possible Mechanism for Inhibition of Angiogenesis by Angiostatic Steroids: Induction of Capillary Basement Membrane Dissolution, Endocrinology Vol. 119:1768-1775, 1986.
A group of tetrahydro steroids useful in inhibiting angiogenesis is disclosed in U.S. Pat. No. 4,975,537, Aristoff, et al. The compounds are disclosed for use in treating head trauma, spinal trauma, septic or traumatic shock, stroke, and hemorrhage shock. In addition, the patent discusses the utility of these compounds in embryo implantation and in the treatment of cancer, arthritis, and arteriosclerosis. Some of the steroids disclosed in Aristoff et al. are disclosed in U.S. Pat. No. 4,771,042 in combination with heparin or a heparin fragment for inhibiting angiogenesis in a warm blooded animal.
Compositions of hydrocortisone, “tetrahydrocortisol-S,” and U-72,745G, each in combination with a beta cyclodextrin, have been shown to inhibit corneal neovascularization: Li, et al., Angiostatic Steroids Potentiated by Sulphated Cyclodextrin Inhibit Corneal Neovascularization, Investigative Ophthalmology and Visual Science, Vol. 32(11):2898-2905, October, 1991. The steroids alone reduce neovascularization somewhat but are not effective alone in effecting regression of neovascularization.
Tetrahydrocortisol (THF) has been disclosed as an angiostatic steroid in Folkman, et al., Angiostatic Steroids, Ann. Surg., Vol. 206(3), 374-383, 1987, wherein it is suggested angiostatic steroids may have potential use for diseases dominated by abnormal neovascularization, including diabetic retinopathy, neovascular glaucoma, and retrolental fibroplasia.
It has been previously shown that certain nonsteroidal anti-inflammatory drugs (NSAIDs) can inhibit angiogenesis and vascular edema in pathologic conditions. The ability of most NSAIDs to influence vascular permeability, leading to edema, and angiogenesis appears to be associated with their ability to block the cyclo-oxygenase enzymes (COX-1 and -2). Blockade of COX-1 and -2 is associated with a decrease in inflammatory mediators, such as PGE2. Moreover, it appears that PGE2 inhibition results in decreased expression and production of various cytokines including vascular endothelial growth factor (VEGF). VEGF is known to produce vascular leakage and angiogenesis in the eye of preclinical models. Also, increased levels of VEGF have been found in neovascular tissues and extracellular fluid from the eyes of patients with diabetic retinopathy and age-related macular degeneration. Thus, NSAIDs may inhibit vascular leakage and angiogenesis by modulating PGE2 levels and its effects on VEGF expression and activity. This theory is supported by work involving animal tumor models which demonstrate that systemic administration of COX-2 inhibitors decreases PGE2 and VEGF tissue levels and thereby prevents tumor-induced angiogenesis. In these models, VEGF activity and angiogenesis are restored by adding exogenous PGE2 during continued COX-2 blockade. However, NSAIDs appear to have variable activity in animal models of ocular neovascularization (NV), in that selective COX inhibitors do not appear to inhibit choroidal neovascularization. In fact, these studies have called into question the role of COX-1 and/or COX-2 in the development of CNV.
As described in commonly owned U.S. application Ser. No. 09/929,381, it was found that certain 3-benzoylphenylacetic acids and derivatives, which are NSAIDs, are useful for treating angiogenesis-related disorders.
Lee et. al. have disclosed that compounds 1 and 2 inhibit LTB4-induced chemotaxis of neutrophils as potently as lipoxin A4 [Lee et. al., Biochemical and Biophysical Research Communications 1991, 180(3), 1416-21]. It is unclear if 1 and 2 act via activation of the lipoxin A4 receptor (ALXR), as the authors did not attempt to reverse their chemotaxis inhibition using an ALXR antibody or small molecule functional antagonist. No other biological data for compounds 1 or 2 has appeared in the art.

Lipoxin A4 and certain analogs thereof have been reported to be anti-inflammatory agents (see for example Serhan et. al., U.S. Pat. No. 5,441,951). It has been reported that aspirin treatment of activated leukocytes induces the biosynthesis of 15-epi-lipoxin A4 (aspirin-triggered lipoxin or ATL) from arachidonic acid, by converting the cyclooxygenase activity of the COX-2 isozyme into lipoxygenase activity [Serhan, Charles N. et. al., J. Pharmacol. Exp. Ther. 1998, 287, 779; Serhan, Charles N. et. al. Clin. Chem. Lab. Med. 1999, 37, 299].

Aspirin has also been associated with anti-cancer [Current Topics in Pharmacology 2002, 6, 25-39; Nature Medicine (New York) 1999, 5(12), 1348-1349] and anti-angiogenesis effects, which may occur partly through the intermediacy of ATL [Anticancer Research 2001, 21(6A), 3829-3837; JP 08268886 A2 (CAN 126:65396); the use of aspirin in combination with the diphenylcyanopentenoic acid, satigrel, for treating diabetic retinopathy is also disclosed in this application]. Lipoxin analog 3 has been shown to inhibit both VEGF- and leukotriene D4-induced endothelial cell chemotaxis and proliferation in vitro, and to inhibit VEGF-induced angiogenesis in a murine chronic granulomatous air pouch model in vivo [Fierro et al., J. Pharm. Expt. Ther. 2002, 300(2), 385-392].

The use of lipoxin A4 and certain analogs, including 3, for treating angiogenesis-dependent diseases, including ocular neovascular diseases such as age-related macular degeneration and diabetic retinopathy, has been disclosed (Serhan and Fierro, U.S. Pat. No. 6,627,658 B1). However to the best of our knowledge no compounds of formula I have been claimed for posterior segment ocular disorders such as AMD and diabetic retinopathy or cellular hyperproliferative and angiogenesis-dependent diseases such as cancer, rheumatoid arthritis, and coronary artery restenosis after balloon angioplasty.